1. Field of the Invention
This invention relates to a metallic card clothing for use in a carding machine.
2. Description of the Prior Art
Conventionally, the metallic card clothing in the carding machine used for the preparation of fibers in the spinning process has been produced by planting staples a, i.e. steel wires bent in the shape illustrated in FIG. 1 in a fillet b, i.e. a web formed of superposed layers of cotton cloth or felt as illustrated in FIG. 2 thereby forming a long needle belt (card clothing) and placing this needle belt to cover the rollers of the carding machine.
In the card clothing so constructed, however, since the acting angle .alpha. and the rear angle .beta. of the needles are parallel, fibers readily sink between the needles and the normal carding action (the action of arranging long fibers in one direction and removing short fibers and impurities) is not started until the sinking fibers c accumulate to a certain thickness. Thus, for the card clothing of this class, the sinking of fibers has always been an indispensable requirement. When the amount of sinking fibers increases excessively, however, the space intended for the carding action becomes excessively small. As the result, the card clothing experiences difficulty in effecting a normal carding operation. When the card clothing of this nature is used, therefore, becomes necessary to perform repeatedly an uneconomical cleaning work called "row cleaning" and, further, to give grinding to the card clothing. For this purpose, the carding machine must be stopped frequently and the working ratio of the carding machine is consequently lowered.
In the circumstance, the metallic card clothing which is produced by having a row of profile wires of an L-shaped cross section as illustrated in FIG. 4 each punched in a serrated pattern as illustrated in FIG. 3, thermally treating the pointed ends of the serrated edges, and wrapping the row of profile wires now containing hardened serrated edges around the rollers of the carding machine has come to find growing acceptance.
In the metallic card clothing so constructed, since the needles a' have a larger acting angle .alpha. than a rear angle .beta. and, therefore, possess a large included angle .gamma., the metallic card clothing exhibits quality and properties widely different from the card clothing having absolutely no included angle as illustrated in FIG. 1 and FIG. 2. As the result, the needle height h.sub.2 of the metallic card clothing is notably smaller than the needle height h.sub.1 of the aforementioned card clothing. This decreased needle height coupled with the improved properties mentioned above constitutes one of the major factors for elimination of sinking fibers. Generally, a decrease of needle height implies a proportional decrease of service life of needles by abrasion. Since the needle points of the metallic card clothing have no use for the bending step which is indispensable to the card clothing illustrated in FIG. 1 and FIG. 2, they can be hardened to a desired level by quenching and consequently prevented from accelerated wear. The fact that the needle height h.sub.2 is relatively small does not matter very much. The metallic card clothing, accordingly, can withstand a protracted continuous service.
Since the metallic card clothing excels the conventional card clothing in terms of properties, quality of the product of carding, price, and the like, it has found widespread acceptance.
The appearance of synthetic fibers has posed a problem to bear upon effective use of these metallic card clothings; these fibers entangle themselves between the needles on the cylinder rollers and impede further progress of the carding operation. The synthetic fibers, because of their high friction coefficient, settle in the spaces intervening between the adjacent rows of needles and do not easily rise from the spaced. The synthetic fibers so deposited fast prevent the needles on the opposed sylinder rollers from effectively interacting. This phenomenon of clinging synthetic fibers impedes effective operation of the metallic card clothing.
For the prevention of this phenomenon, there may be conceived an idea of widening the acting angle of the needles or increasing the included angle of the needles on the cylinder rollers thereby preventing the fibers from settling to the intervening spaces. This idea, however, cannot be adopted because the increased working angle or included angle of the needles results in an impaired carding effect and a lowered quality of the product of carding.
It is the metallic card clothing illustrated in FIG. 5 and FIG. 6 that has been developed for the solution of this problem. This metalic card clothing comprises a row of profile wires rolled in an L-shaped cross section as illustrated in FIG. 6 similarly to the profile wires used in the conventional metallic card clothing, which profile wires are punched in a serrated pattern containing spaced needles a" each forming a positive or acute acting angle .alpha. in the leading end portion and a negative or obtuse acting angle .alpha.' (not less than 90.degree.) in the basal portion and, consequently, fulfilling two entirely different actions.
The operation of this metallic card clothing will be described below with reference to FIG. 7. A fiber impinging on the point O exerts a force OA upon the needle in consequence of the rotation of the cylinder roller. In accordance with the theory of vector, the force with which the fiber is drawn in is expressed as OB. The needle, tends to draw the fiber into the space with the force of OB. Incidentally, the space of the portion indicated by X in the diagram constitutes a space wherein the needle in question and the directly opposite needle on the other cylinder roller are allowed to interact amply. Any fibers falling in this space, therefore, are not suffered to entangle themselves in the intervening space and induce the phenomenon of fiber sinking. When a fiber is forced into the space indicated by Y in the diagram in consequence of excessive supply of fibers exerts a force of O'A' upon the needle. Again by the theory of vector, the force O'A' of the fiber acting at the point O' is resolved into the component forces O'B' and O'C'. Consequently, the force O'B' is exerted upwardly entirely contrary to the aforementioned drawing force OB. As the result, the rotation of the cylinder roller causes all the fibers in the space Y to be moved into the space X and subjected to the carding action of the card clothing. Thus, even the fibers which are liable to entangle themselves on the cylinder roller can be easily enabled to undergo the carding action.
The metallic card clothing constructed as described above offers an appreciable solution to the problem in terms of the function of a card clothing. The manufacture of this metallic card clothing remains to be rather difficult because it entails the step of punching the profile wires in the serrated pattern. It suffers from a major problem of heavy loss of material. The desirability of the appearance of a metallic card clothing enjoying high quality and excelling in resistance to wear finds mounting recognition as demands for increased machine speeds and improved productivity are gaining in impetus as experienced nowaday.
In the carding machine using the conventional metallic card clothing, an effort to improve productivity is liable to result in conception of an idea of increasing the total number of needles participating in the manifestation of the carding action where the individual needles possess a fixed amount of ability. In fact, the idea of increasing the number of needles per unit area by narrowing the pitches separating the individual needles or the intervals separating the rows of such needles has been already reduced to practise. Naturally, the combination between the pitches and the intervals separating the rows constitutes itself an important factor. When the density of the needles is increased randomly, there may ensue the problem of deposition of extraneous matter. There is another problem that the narrowed spaces between the needles render difficult desired plunge of needles into the web of fibers. Thus, the carding action of the card clothing is seriously impaired. The number of needles per unit area, therefore, is not allowed to increase past a certain level. Moreover, the increase in the number of needles turns out to be an immense addition to the work load involved in the conventional method for the manufacture of a metallic card clothing which comprises rolling thin round wires into profile wires and punching thin flat portions of the rolled profile wires in a serrated pattern containing teeth at a fine pitch. When the intervals separating the rows of needles are narrowed, the total length of the serrated profile wires to be wound on the cylinder rollers is all the more increased and the work involved becomes more troublesome. Thus, the manufacture of such profile wires and the attachment thereof to the cylinder rollers call for huge time and labor.
Since the conventional metallic card clothing is manufactured by the punching of rolled profile wires, it suffers from the disadvantage that the work is relatively difficult and it entails loss of material. It further has a problem pertaining to resistance to wear. Generally in the case of a rolled wire, fibrous carbide segments are distributed in the rolled wire in the direction of rolling. During the course of manufacture of a metallic card clothing as described above, the punching of the profile wire for the formation of needles inevitably entails severance of the aforementioned fibrous carbide segments. As the result, the fibrous carbide segments originating in steel wires are arrayed in the longitudinal direction of the metal card clothing (in the direction indicated by the arrow of a dotted line in FIG. 5) and the fibers act on the working surfaces of the needles (indicated by the symbol w in FIG. 5) in the direction in which the fibrous carbide segments are arrayed. The working surfaces of the needles, therefore, offer no ample resistance to wear and tend to wear off in a zigzagging pattern.